There are interactions in the effects of VDT luminance contrast and screen luminance on the operator's visual performance. The range of both optimal and proper contrast is the function of the level of background luminance on the screen. Increasing screen luminance results in a shift from optimal and proper contrast towards low contrast. The subjective evaluation method has the same validity as the performance index in assessing VDT display quality.

On the standardization of VDT's proper and optimal contrast range

Traditional steady - state visual evoked potential (SSVEP) using light flicker stimulation may easy cause visual fatigue with a consequent reduction of recognition accuracy. In the previous study, we proposed a steady - state motion visual evoked potential (SSMVEP) brain - computer interface (BCI) method. A black - white ring - shaped checkerboard was used as the visual stimulus paradigm in this study. The movement patterns of the checkerboard included contraction and expansion. Based on the signal-to-noise ratio (SNR), recognition accuracy and anti-fatigue properties, the effects of black-white brightness contrast on the brain response were investigated. Experimental results indicated that when the contrast ratio was the highest, it could obtain higher recognition accuracy and SNR, yet it was easy to cause visual fatigue. When the contrast was the lowest, the sensitivity of the eyes against flicker reduced to the lowest, and it could reduce visual fatigue. However the recognition accuracy and SNR were low. In contrast, the appropriate contrast could guarantee high SNR and recognition accuracy, and as much as possible to reduce the visual fatigue.

Study on the effects of brightness contrast on steady-state motion visual evoked potential

Physiological receptors have different sensitive degrees to stimuli of different intensities. Eyes as an ordinary perceptive organ have different resolution thresholds to the gray scales stimuli of different intensities. This study under the ideal illuminations adopts constant-stimuli method in psychophysicals experiment methods to analyze the change rules of visual threshold perspectives when target grayscale and threshold perspective change alternatively. This study has total 20 subjects, 6 background grey levels and 11 kinds of perspectives to obtain the change rules of visual threshold perspectives for different background grey levels under the 400 lx illumination, taking the grayscale ratio under 50 % recognition rate as the grayscale ratio of the threshold perspective, taking that under 95 % recognition rate as the grayscale ratio required for basically no perspective error, and obtain the corresponding fitting formula to provide the referential basis for designs.

Study on the Change Rules of Visual Threshold Perspectives of Different Background Grayscales Under the Ideal Illumination

L'ergonomie est une science jeune en Chine. Ce fut seulement apres la fondation de la Republique Populaire de Chine en 1949 que des efforts systematiques furent entrepris dans ce champ. Cet article passe en revue brievement l'histoire de l'ergonomie chinoise et decrit les chapitres principaux de la recherche ergonomique en Chine, dans la derniere decennie: description et evaluation des interfaces homme/machine, etude de l'environnement et son controle, mesure des charges de travail et etudes anthropometriques.



Ergonomics is a young science in China. It was only after the founding of the People's Republic of China in 1949 that some systematic efforts were started in this field. This paper briefly reviews the history of Chinese ergonomics and describes the main areas of ergonomic research in China in the last decade. These areas are the design and evaluation of human-machine interfaces, environmental design and control, the measurement of workload, and anthropometric studies.

The Development of Ergonomics in China

Contributions of Psychology to China's Standardization

The visual performance of Chinese adults, 20 to 30 years of age, is evaluated as a part of a study determining illumination standards intended for use in The People's Republic of China. Spatial acuity was measured with Landolt rings as a function of visual angle, contrast and illuminance. The influence of these variables on visual performance is described by a mathematical model. The results are compared with the standard RCS visual performance curve recommended by the CIE.

B.L. Yu

Papers

Visual performance of young Chinese observers